I. Field of the Invention
The present invention relates to fluid flow meters.
II. Description of the Prior Art
There are a number of previously known fluid flow meters which measure the rate of fluid flow through the flow meter. For example, in one type of previously known flow meters, a movable vane creates a variable size opening between the outer periphery of the vane and a housing wall. A spring urges the vane to a closed position while, conversely, fluid flow urges the vane to an open position. Thus, as the fluid flow increases, the vane rotates to a more open position than with a lower fluid flow rate and vice versa. The actual rotational position of the vane provides an indication of the fluid flow rate.
In still another type of fluid flow meter, an orifice is provided between the inlet and the outlet while a tapered needle is positioned within the orifice to variably restrict it. Either the orifice or the needle is movable in response to fluid flow thus varying the fluid restriction of the orifice in accordance with the fluid flow rate. A mechanical detector determines the position of the movable member, i.e. either the tapering needle or the orifice, and this position provides an indication of the fluid flow rate through the flow meter.
All these previously known flow meters, however, do not provide a highly accurate indication of a fluid flow rate and thus are unsuitable for numerous applications.